An ancient tropical origin, dispersals via land bridges and Miocene diversification explain the subcosmopolitan disjunctions of the liverwort genus Lejeunea

Understanding the biogeographical and diversification processes explaining current diversity patterns of subcosmopolitan-distributed groups is challenging. We aimed at disentangling the historical biogeography of the subcosmopolitan liverwort genus Lejeunea with estimation of ancestral areas of origin and testing if sexual system and palaeotemperature variations can be factors of diversification. We assembled a dense taxon sampling for 120 species sampled throughout the geographical distribution of the genus. Lejeunea diverged from its sister group after the Paleocene-Eocene boundary (52.2 Ma, 95% credibility intervals 50.1-54.2 Ma), and the initial diversification of the crown group occurred in the early to middle Eocene (44.5 Ma, 95% credibility intervals 38.5-50.8 Ma). The DEC model indicated that (1) Lejeunea likely originated in an area composed of the Neotropics and the Nearctic, (2) dispersals through terrestrial land bridges in the late Oligocene and Miocene allowed Lejeunea to colonize the Old World, (3) the Boreotropical forest covering the northern regions until the late Eocene did not facilitate Lejeunea dispersals, and (4) a single long-distance dispersal event was inferred between the Neotropics and Africa. Biogeographical and diversification analyses show the Miocene was an important period when Lejeunea diversified globally. We found slight support for higher diversification rates of species with both male and female reproductive organs on the same individual (monoicy), and a moderate positive influence of palaeotemperatures on diversification. Our study shows that an ancient origin associated with a dispersal history facilitated by terrestrial land bridges and not long-distance dispersals are likely to explain the subcosmopolitan distribution of Lejeunea. By enhancing the diversification rates, monoicy likely favoured the colonisations of new areas, especially in the Miocene that was a key epoch shaping the worldwide distribution.

Transformation of Riccia fluitans, an Amphibious Liverwort Dynamically Responding to Environmental Changes

The colonization of land by streptophyte algae, ancestors of embryophyte plants, was a fundamental event in the history of life on earth. Bryophytes are early diversifying land plants that mark the transition from freshwater to terrestrial ecosystems. The amphibious liverwort Riccia fluitans can thrive in aquatic and terrestrial environments and thus represents an ideal organism to investigate this major transition. Therefore, we aimed to establish a transformation protocol for R. fluitans to make it amenable for genetic analyses. An Agrobacterium transformation procedure using R. fluitans callus tissue allows to generate stably transformed plants within 10 weeks. Furthermore, for comprehensive studies spanning all life stages, we demonstrate that the switch from vegetative to reproductive development can be induced by both flooding and poor nutrient availability. Interestingly, a single R. fluitans plant can consecutively adapt to different growth environments and forms distinctive and reversible features of the thallus, photosynthetically active tissue that is thus functionally similar to leaves of vascular plants. The morphological plasticity affecting vegetative growth, air pore formation, and rhizoid development realized by one genotype in response to two different environments makes R. fluitans ideal to study the adaptive molecular mechanisms enabling the colonialization of land by aquatic plants.

The identification of differentially expressed genes in male and female gametophytes of simple thalloid liverwort Pellia endiviifolia sp. B using an RNA-seq approach

MAIN CONCLUSION

This study shows differences in gene expression between male and female gametophytes of the simple thalloid liverwort with a distinction between the vegetative and reproductive phases of growth. Pellia endiviifolia is a simple thalloid liverwort that, together with hornworts and mosses, represents the oldest living land plants. The limited taxon sampling for genomic and functional studies hampers our understanding of processes governing evolution of these plants. RNA sequencing represents an attractive way to elucidate the molecular mechanisms of non-model species development. In the present study, RNA-seq was used to profile the differences in gene expression between P. endiviifolia male and female gametophytes, with a distinction between the vegetative and reproductive phases of growth. By comparison of the gene expression profiles from individuals producing sex organs with the remaining thalli types, we have determined a set of genes whose expression might be important for the development of P. endiviifolia reproductive organs. The selected differentially expressed genes (DEGs) were categorized into five main pathways: metabolism, genetic information processing, environmental information processing, cellular processes, and organismal systems. A comparison of the obtained data with the Marchantia polymorpha transcriptome resulted in the identification of genes exhibiting a similar expression pattern during the reproductive phase of growth between members of the two distinct liverwort classes. The common expression profile of  87 selected genes suggests a common mechanism governing sex organ development in both liverwort species. The obtained RNA-seq results were confirmed by RT-qPCR for the DEGs with the highest differences in expression level. Five Pellia-female-specific and two Pellia-male-specific DEGs showed enriched expression in archegonia and antheridia, respectively. The identified genes are promising candidates for functional studies of their involvement in liverwort sexual reproduction.

The Increase of Simple Sequence Repeats during Diversification of Marchantiidae, An Early Land Plant Lineage, Leads to the First Known Expansion of Inverted Repeats in the Evolutionarily-Stable Structure of Liverwort Plastomes

The chloroplast genomes of liverworts, an early land plant lineage, exhibit stable structure and gene content, however the known resources are very limited. The newly sequenced plastomes of Conocephalum, Riccia and Sphaerocarpos species revealed an increase of simple sequence repeats during the diversification of complex thalloid liverwort lineage. The presence of long TA motifs forced applying the long-read nanopore sequencing method for proper and dependable plastome assembly, since the length of dinucleotide repeats overcome the length of Illumina short reads. The accumulation of SSRs (simple sequence repeats) enabled the expansion of inverted repeats by the incorporation of rps12 and rps7 genes, which were part of large single copy (LSC) regions in the previously sequenced plastomes. The expansion of inverted repeat (IR) at the genus level is reported for the first time for non-flowering plants. Moreover, comparative analyses with remaining liverwort lineages revealed that the presence of SSR in plastomes is specific for simple thalloid species. Phylogenomic analysis resulted in trees confirming monophyly of Marchantiidae and partially congruent with previous studies, due to dataset-dependent results of Dumortiera-Reboulia relationships. Despite the lower evolutionary rate of Marchantiales plastomes, significant barcoding gap was detected, even for recently divergent holarctic Conocephalum species. The sliding window analyses revealed the presence of 18 optimal (500 bp long) barcodes that enable the molecular identification of all studied species.

Phytofiltration of chosen metals by aquarium liverwort (Monosoleum tenerum)

Aquatic bryophytes are widely used as indicators of water pollution with various substances, including metals. We present a first study concerning the feasibility of Monosoleum tenerum to remove potentially toxic metals Zn, Cu, Ni, Mn and Fe from water. The novel approach to study the bioaccumulation under controlled conditions and in vitro grown aquarium liverworts was applied. The plants were exposed to 1, 10 and 100 ppm multi-metal solution for 7 days and subsequently the metal content was determined in plant material and media to calculate the bioaccumulation factor (BAF). The study revealed various accumulation behavior (metal and dose dependent), which followed the order of Cu > Zn > Mn > Ni > Fe for 1 ppm; Zn > Cu > Mn > Fe > Ni for 10 ppm and Cu > Fe > Zn > Ni > Mn for 100 ppm solution. However, with increasing Cu, Mn and Ni concentration in the solution, BAF decreased. For Zn the highest BAF value (136) was obtained for the 10 ppm solution. Fe bioaccumulation increased with the increasing solution concentration. After 7 week exposure, the results indicated highest accumulation of Cu (3,25 mg) followed by Fe (1,8 mg) in the plant tissue for the 100 ppm solution. Overall, the bryophyte M. tenerum demonstrate high potential for the removal of toxic metals from the multi-metal solution via accumulation in plant tissue. The BAF values were proper to indicate the use of M. tenerum for phytofiltration of waste waters affected by Zn, Cu, Ni, Mn and Fe.

Archetypal Roles of an Abscisic Acid Receptor in Drought and Sugar Responses in Liverworts

Abscisic acid (ABA) controls seed dormancy and stomatal closure through binding to the intracellular receptor Pyrabactin resistance1 (Pyr1)/Pyr1-like/regulatory components of ABA receptors (PYR/PYL/RCAR) in angiosperms. Genes encoding PYR/PYL/RCAR are thought to have arisen in the ancestor of embryophytes, but the roles of the genes in nonvascular plants have not been determined. In the liverwort Marchantia polymorpha, ABA reduces growth and enhances desiccation tolerance through increasing accumulation of intracellular sugars and various transcripts such as those of Late Embryogenesis Abundant (LEA)-like genes. In this study, we analyzed a gene designated MpPYL1, which is closely related to PYR/PYL/RCAR of angiosperms, in transgenic liverworts. Transgenic lines overexpressing MpPYL1-GFP showed ABA-hypersensitive growth with enhanced desiccation tolerance, whereas Mppyl1 generated by CRISPR-Cas9-mediated genome editing showed ABA-insensitive growth with reduced desiccation tolerance. Transcriptome analysis indicated that MpPYL1 is a major regulator of abiotic stress-associated genes, including all 35 ABA-induced LEA-like genes. Furthermore, these transgenic plants showed altered responses to extracellular Suc, suggesting that ABA and PYR/PYL/RCAR function in sugar responses. The results presented here reveal an important role of PYR/PYL/RCAR in the ABA response, which was likely acquired in the common ancestor of land plants. The results also indicate the archetypal role of ABA and its receptor in sugar response and accumulation processes for vegetative desiccation tolerance in bryophytes.

Boron and the evolutionary development of roots

Experimental work has shown that Boron (i.e., Boric acid, B) is an essential and multifunctional microelement for vascular plant development. In addition to its other functions, which include xylem development and lignin biosynthesis, we now know that B is involved in phytohormone-signaling and influences the mechanical properties of intercellular pectins. From these data, we conclude that B played an important role during the evolutionary development of lignified tissues, and that it may have been involved in the evolution of vascular plant roots, as hypothesized by D. H. Lewis in 1980. Herein, we review the data pertaining to Lewis' hypothesis, present experimental results on the role of B in root (vs. rhizoid) formation in sunflower vs. a liverwort, and describe the appearance of roots in the fossil record. Open questions are addressed, notably the lack of our knowledge concerning soil microbes and their interactive roles with the micronutrient B during root formation.

Female-specific gene expression in dioecious liverwort Pellia endiviifolia is developmentally regulated and connected to archegonia production

BACKGROUND

In flowering plants a number of genes have been identified which control the transition from a vegetative to generative phase of life cycle. In bryophytes representing basal lineage of land plants, there is little data regarding the mechanisms that control this transition. Two species from bryophytes - moss Physcomitrella patens and liverwort Marchantia polymorpha are under advanced molecular and genetic research. The goal of our study was to identify genes connected to female gametophyte development and archegonia production in the dioecious liverwort Pellia endiviifolia species B, which is representative of the most basal lineage of the simple thalloid liverworts.

RESULTS

The utility of the RDA-cDNA technique allowed us to identify three genes specifically expressed in the female individuals of P.endiviifolia: PenB_CYSP coding for cysteine protease, PenB_MT2 and PenB_MT3 coding for Mysterious Transcripts1 and 2 containing ORFs of 143 and 177 amino acid residues in length, respectively. The exon-intron structure of all three genes has been characterized and pre-mRNA processing was investigated. Interestingly, five mRNA isoforms are produced from the PenB_MT2 gene, which result from alternative splicing within the second and third exon. All observed splicing events take place within the 5'UTR and do not interfere with the coding sequence. All three genes are exclusively expressed in the female individuals, regardless of whether they were cultured in vitro or were collected from a natural habitat. Moreover we observed ten-fold increased transcripts level for all three genes in the archegonial tissue in comparison to the vegetative parts of the same female thalli grown in natural habitat suggesting their connection to archegonia development.

CONCLUSIONS

We have identified three genes which are specifically expressed in P.endiviifolia sp B female gametophytes. Moreover, their expression is connected to the female sex-organ differentiation and is developmentally regulated. The contribution of the identified genes may be crucial for successful liverwort sexual reproduction.

Novel genes specifically expressed during the development of the male thalli and antheridia in the dioecious liverwort Pellia endiviifolia

In bryophytes (lower plants), sex determination is manifested in the gametophyte generation by the production of egg- and sperm-forming gametangia. We identified four genes specifically expressed in the male thalli of dioecious liverwort Pellia endiviifolia species B using RDA-cDNA method. These are: PenB_TUA1 coding for an α-tubulin family protein, PenB_Raba1/11 coding for a Rab family protein, PenB_HMG-box coding for an HMG-box family protein and PenB_MT coding for an unknown transcript that contains an ORF of 295 amino acid residues. The expression of identified genes shows developmental and environmental regulation. PenB_TUA1 and PenB_Raba1/11 are expressed in the male thalli, regardless of whether they develop antheridia. PenB_HMG-box and PenB_MT are exclusively expressed in the male thalli-producing antheridia while growing in the field. Moreover, two genes PenB_TUA1 and PenB_Raba1/11 are encoded only in the male genome of P. endiviifolia sp B. Our studies show for the first time the specific contribution of identified genes in the liverwort male gametophyte development. In higher plants, correct regulation of α-tubulin and Rab family genes activity is essential for tip-focused membrane trafficking and growth of the male gametophyte. Thus these genes are critical to the reproductive success of these plants. Plant HMG-box proteins bind DNA and may affect chromatin structure, promoting the assembly of nucleoprotein complexes that control DNA-dependent processes including transcription. Our results show that genes connected with the gametogenesis processes are evolutionarily conserved from the liverworts - the oldest living land plants, to higher plants.

Influence of soil fumigation by methyl bromide and methyl iodide on rhizosphere and phyllosphere microbial community structure

Rhizosphere and phyllosphere microbial communities were evaluated on roots and leaves of growth chamber-grown lettuce (Lactuca sativa (L.) cv. Green Forest) plants by culture-dependent and -independent methods after soil fumigation. Denaturing gradient gel electrophoresis (DGGE) with 16S rRNA primers followed by cloning and sequencing was used to identify major rRNA bands from the rhizosphere and phyllosphere. Three weeks after fumigation, there were no differences (P = 0.16) in rhizosphere microbial communities between the fumigated treatments and the control. The same effect was observed during week seven after fumigation (P=0.49). Also, no significant differences (P=0.49) were found in the phyllosphere microbial communities between the fumigated treatments and the control during the growth period of the plant. A majority of the bands in the rhizosphere were related to known bacterial sequences with a 96 to 100 % sequence similarity. Some of the derived sequences were related to Pseudomonas syringae pv. tomato DC300 and Bradyrhizobium japonicum USDA 110. A total of 23 isolates were identified from leaf surface by both culture-dependent and independent methods, and only Photorhabdus luminescens was found on leaf surface using both techniques. All the Biolog isolates from phyllosphere were from the Proteobacteria phylum compared to the culture-independent bands from the leaves that were from different bacterial phyla. Based on our data, methyl bromide (MeBr) and methyl iodide (MeI) did not have any significant negative effects on rhizosphere and phyllosphere microbial communities throughout the growing period of lettuce.

Sebacinales are associates of the leafy liverwort Lophozia excisa in the southern maritime Antarctic

The leafy liverwort Lophozia excisa, which is colonised by basidiomycete fungi in other biomes and which evidence suggests may be colonised by mycorrhizal fungi in Antarctica, was sampled from Léonie Island in the southern maritime Antarctic (67 degrees 36' S, 68 degrees 21' W). Microscopic examination of plants indicated that fungal hyphae colonised 78% of the rhizoids of the liverwort, apparently by entering the tips of rhizoids prior to growing into their bases, where they formed hyphal coils. Extensive colonisation of stem medullary cells by hyphae was also observed. DNA was extracted from surface-sterilised liverwort tissues and sequenced following nested PCR, using the primer set ITS1F/TW14, followed by a second round of amplification using the ITSSeb3/TW13 primer set. Neighbour-joining analyses showed that the sequences obtained nested in Sebacinales clade B as a 100% supported sister group to Sebacinales sequences from the leafy liverworts Lophozia sudetica, L. incisa and Calypogeia muelleriana sampled from Europe. Direct PCR using the fungal specific primer set ITS1F/ITS4 similarly identified fungi belonging to Sebacinales clade B as the principal colonists of L. excisa tissues. These observations indicate the presence of a second mycothallus in Antarctica and support the previous suggestion that the Sebacinales has a wide geographical distribution.

Conservative ecological and evolutionary patterns in liverwort-fungal symbioses

Liverworts, the most ancient group of land plants, form a range of intimate associations with fungi that may be analogous to the mycorrhizas of vascular plants. Most thalloid liverworts contain arbuscular mycorrhizal glomeromycete fungi similar to most vascular plants. In contrast, a range of leafy liverwort genera and one simple thalloid liverwort family (the Aneuraceae) have switched to basidiomycete fungi. These liverwort switches away from glomeromycete fungi may be expected to parallel switches undergone by vascular plants that target diverse lineages of basidiomycete fungi to form ectomycorrhizas. To test this hypothesis, we used a cultivation-independent approach to examine the basidiomycete fungi associated with liverworts in varied worldwide locations by generating fungal DNA sequence data from over 200 field collections of over 30 species. Here we show that eight leafy liverwort genera predominantly and consistently associate with members of the Sebacina vermifera species complex and that Aneuraceae thalloid liverworts associate nearly exclusively with Tulasnella species. Furthermore, within sites where multiple liverwort species co-occur, they almost never share the same fungi. Our analyses reveal a strikingly conservative ecological and evolutionary pattern of liverwort symbioses with basidiomycete fungi that is unlike that of vascular plant mycorrhizas.

Desiccation tolerance in red and green gametophytes of Jamesoniella colorata in relation to photoprotection

This study tests the hypothesis that red-leaved gametophytes of the liverwort Jamesoniella colorata (Lehm.) Schiffn., which are found in relatively dry habitats, are more desiccation tolerant than their green counterparts, which are found in moister environments, through superior photoprotective systems. The potential role of red foliar pigments in relation to water deficits is investigated by measuring cell water-relations, oxidative damage and photosynthetic responses. The presence of red pigments, or other cellular constituents, did not affect cell water-relations during dehydration and thus appear not to be involved in cell osmotic regulation. During drying, both colour morphs showed a similar non-photochemical quenching activity and did not experience significant oxidative damage, as measured by the amounts of ascorbate, malondialdehyde and photosynthetic pigments. However, the levels of oxidative damage increased directly upon rewetting the gametophytes, especially in low light conditions (25 micromol m(-2) s(-1)). The efficiency of photosystem II only recovered partially after severe water deficits in both phenotypes. However, the red gametophytes recovered faster and more completely from mild water deficits than did the greens. Moreover, they experienced significantly less photobleaching after rehydration in low light. It is suggested that red pigments and/or carotenoids in these gametophytes improve desiccation tolerance by alleviating photooxidative damage.

Does Lunularia cruciata form symbiotic relationships with either Glomus proliferum or G. intraradices?

The present study was undertaken to investigate whether the behaviour in vitro of Lunularia cruciata grown with Glomus intraradices and G. proliferum, on SRV medium with 29.2 mM sucrose satisfies the requirements of Koch' postulates for mutualistic symbiosis. Hyphae emerging from mycothallus were able to grow over a two-compartment Petri dish barrier and capture and translocate phosphorus into the host liverwort. Thus, there were increases in plant dry weight, higher AM fungi spore production, and higher plant total phosphorus content. Moreover, this colonization of L. cruciata reproduces typical symptoms generally associated with mycorrhizae. These results showed that mycothalli of L. cruciata have available functionalities generally associated with mycorrhizal symbiosis in higher plants; however, the energy/photosynthetic carbon requirements to maintain a mutualistic symbiosis may be a limiting factor in vivo. Features here discussed indicate that, at least in tested experimental conditions, the endophytic association of L. cruciata with both G. intraradices and G. proliferum is a parasitic/opportunistic partnership rather than a mutualistic symbiosis.

Cluster formation in liverwort-associated methylobacteria and its implications

Pink-pigmented methylotropic bacteria of the genus Methylobacterium inhabit the surfaces of plant organs. In bryophytes, these methylobacteria enhance cell growth, but the nature of this plant-microbe interaction is largely unknown. In this study, methylobacteria were isolated from the upper surface of the free-living thalli of the liverwort Marchantia polymorpha L. Identification of one strain by 16S ribosomal RNA (rRNA) gene-targeted polymerase chain reaction (PCR) and other data show that these microbes represent an undescribed species of the genus Methylobacterium (Methylobacterium sp.). The growth-promoting activity of these wild-type methylobacteria was tested and compared with that of the type strain Methylobacterium mesophilicum. Both types of methylobacteria stimulated surface expansion of isolated gemmae from Marchantia polymorpha by about 350%. When suspended in water, the liverwort-associated bacteria (Methylobacterium sp.) formed dense clusters of up to 600 cells. In liquid cultures of Methylobacterium mesophilicum, single cells were observed, but no clustering occurred. We suggest that the liverwort-associated methylobacteria are co-evolved symbionts of the plants: Cluster formation may be a behavior that enhances the survival of the epiphytic microbes during periods of drought of these desiccation-tolerant lower plants.

SLOPE ASPECT MODIFIES COMMUNITY RESPONSES TO CLEAR-CUTTING IN BOREAL FORESTS

Slope aspect modifies microclimate and influences ecological processes and spatial distribution of species across forest landscapes, but the impact of slope aspect on community responses to disturbance is poorly understood. Such insight is necessary to understand landscape community dynamics and resilience. We compared bryophyte (liverworts and mosses) communities in matched 0.02-ha plots of four boreal stand types in central Sweden: recently clear-felled and mature stands dominated by Norway spruce in south-facing and north-facing slopes. Differences between forests and clear-cuts were interpreted as effects of clear-cutting, and differences between south- and north-facing slopes as effects of aspect. In response to clear-cutting, bryophyte cover and composition changed more in south-facing slopes. Only one out of ten significantly declining species in south-facing slopes also declined significantly in north-facing slopes. North-facing slopes lost fewer bryophyte species, and among those, fewer forest species and fewer species associated with wood and bark. In north-facing slopes, the average proportions of mosses and liverworts shared between the forest and the clear-cut plot were 88% and 74%, respectively. Corresponding numbers for south-facing slopes were 79% and 33%. In addition, more bryophyte species were added in north- than south-facing slopes after clear-cutting, somewhat reducing the difference in compositional change between aspects. South- and north-facing mature forests differed in species composition, mostly due to higher richness of mosses in south-facing slopes. The smaller changes in bryophyte communities on north-facing slopes in response to clear-cutting have implications for ecosystem dynamics and management as high local survival may enhance landscape-level resilience.

Growth in liverworts of the Marchantiales is promoted by epiphytic methylobacteria

Liverworts, the most basal lineage of extant land plants, have been used as model systems in the reconstruction of adaptations to life on land. In this study, we used gemmae (specialized propagules) that were isolated from mature gemma cups of two distantly related species of liverworts, Marchantia polymorpha L. and Lunularia cruciata L. (order Marchantiales). We show that methylobacteria (genus Methylobacterium), microbes that inhabit the surfaces of land plants where they secrete phytohormones (cytokinines), promote the growth of isolated gemmae cultivated on agar plates. As a control, two species of higher plants, maize (Zea mays L.) and sunflower (Helianthus annuus L.) were raised aseptically from sterile seeds (i.e., caryopses, achenes). Inoculation of these propagules with methylobacteria was without effect on growth in the above-ground phytosphere (expansion of stems and leaves). We conclude that normal development in Marchantia and Lunularia is dependent on (and possibly regulated by) epiphytic methylobacteria, whereas representative higher plants grow at optimal rates in the absence of these prokaryotic epiphytes.

Overgrowth competition, fragmentation and sex-ratio dynamics: a spatially explicit, sub-individual-based model

Sessile organisms that compete for access to resources by overgrowing each other may risk the local elimination of one sex or the other, as frequently happens within clumps of the dioecious liverwort Marchantia inflexa. A multi-stage, spatially implicit differential-equation model of M. inflexa growing in an isolated patch, analysed in a previous study, indicated that long-term coexistence of the sexes within such patches may be only temporary. Here we derive a spatially explicit, sub-individual-based model to reconsider this interpretation when much more ecological realism is taken into account, including the process of fragmentation. The model tracks temporally discrete growth increments in continuous space, representing growth architecture and the overgrowth process in significant geometric detail. Results remain generally consistent with the absence of long-term coexistence of the sexes in individual patches of Marchantia. Dynamics of sex-specific growth qualitatively resemble those generated by differential-equation models, suggesting that this much simpler framework may be adequate for multi-patch metapopulation models. Direct competition between fragmenting and non-fragmenting clones demonstrates the importance of fragmentation in overgrowth competition. The results emphasize the need for empirical work on mechanisms of overgrowth and for modeling and empirical studies of life history tradeoffs and sex-ratio dynamics in multi-patch systems.

Wind as a Long-Distance Dispersal Vehicle in the Southern Hemisphere

Anisotropic (direction-dependent) long-distance dispersal (LDD) by wind has been invoked to explain the strong floristic affinities shared among landmasses in the Southern Hemisphere. Its contribution has not yet been systematically tested because of the previous lack of global data on winds. We used global winds coverage from the National Aeronautics and Space Administration SeaWinds scatterometer to test whether floristic similarities of Southern Hemisphere moss, liverwort, lichen, and pteridophyte floras conform better with (i) the anisotropic LDD hypothesis, which predicts that connection by "wind highways" increases floristic similarities, or (ii) a direction-independent LDD hypothesis, which predicts that floristic similarities among sites increase with geographic proximity. We found a stronger correlation of floristic similarities with wind connectivity than with geographic proximities, which supports the idea that wind is a dispersal vehicle for many organisms in the Southern Hemisphere.

Two types of plastid ftsZ genes in the liverwort Marchantia polymorpha

Two types of ftsZ genes (MpftsZ1 and MpftsZ2) were isolated from the liverwort Marchantia polymorpha by degenerate reverse transcription PCR. The MpFtsZ1 and MpFtsZ2 proteins are predicted to localize in chloroplasts. Genomic Southern analysis suggested that each ftsZ gene is a single-copy nuclear gene. Northern analysis confirmed that both genes are active. A phylogenetic tree constructed with the deduced MpFtsZ amino acid sequences suggests that MpFtsZ1 and MpFtsZ2 can be classified into the plant chloroplastic FtsZ1 and FtsZ2 families, respectively. This result suggests that two ftsZ families exist universally in land plants. The determination of the intron structures of both MpftsZ genes supported this hypothesis. The transformation of a sense MpftsZ2 overexpression construct into M. polymorpha produced a large chloroplast phenotype in a transgenic plant. The mean number of chloroplasts was 38.2 (standard deviation, 21.4; n = 200) in epidermal cells of wild-type plants, whereas the mean number of chloroplasts was 7.4 (standard deviation, 4.4; n = 200) in the transgenic plant. Southern analysis showed that the cauliflower mosaic virus 35S promoter- MpftsZ2 construct was inserted in at least three positions. Northern analysis suggested that the high accumulation of MpftsZ2 mRNA blocked plastid division. Determination of the chlorophyll content and the chlorophyll fluorescence parameters suggested that the macrochloroplasts function like chloroplasts in wild-type plants under normal light conditions. However, the transgenic plant grew more slowly than did wild-type plants.

Biosynthesis of the sesquiterpene hodgsonox from the New Zealand liverwort Lepidolaena hodgsoniae

The incorporation of [1-13C] labelled glucose into hodgsonox, a sesquiterpene epoxide with a unique, doubly allylic ether functionality has been studied in axenic cultures of the liverwort Lepidolaena hodgsoniae. Quantitative 13C NMR spectroscopic analysis showed that the isoprene units are derived exclusively from the methylerythritol phosphate pathway.

Effects of seven pure flavonoids from mosses on germination and growth of Tortula muralis HEDW (Bryophyta) and Raphanus sativus L (Magnoliophyta)

Dried mosses (five moss species) were progressively extracted and subjected to a four-step Craig distribution. Seven pure flavonoids were isolated and identified. The flavonoids were the flavones apigenin, apigenin-7-O-triglycoside, lucenin-2, luteolin-7-O-neohesperidoside, saponarine and vitexin; and the biflavonoid bartramiaflavone and they were submitted to biological tests. The tests were performed in vitro on spore germination and protonemal growth of the moss Tortula muralis and on seed germination and root growth of Raphanus sativus. Flavonoids caused a decrease in the percentage of spore germination, protonemal development and root growth. In addition they caused morphological alterations, such as forked tips, swollen apices, rounded cells and early formation of brood cells in the protonemata. Data were discussed in relation to the presence of allelochemicals in mosses.